The present invention relates to opening arrangements for packing containers, and, more particularly to flexible laminated containers for liquid foods that have a sealed pouring opening.
Packing containers of the non-returnable type for liquid foods or other liquid or pumpable products are made in general of a flexible packing laminate, which comprises layers of fibrous material or thermoplastic material and possibly aluminium foil. The packing laminate is converted to an individual packing container by folding and heat-sealing, and is provided, among other things also with some type of applied opening arrangement. Usually, though, the opening arrangement is constituted of cutting or tearing indications which can be printed onto the outside of the packing laminate to facilitate the removal of a suitable part of the packing container, e.g. a corner. It is also possible to use one of the seals of the packing container as an opening arrangement, the seal being broken on opening and an emergent part of the packing container being able to serve as a pouring spout.
The abovementioned known arrangements and methods for the opening of packing containers of laminated packing material all have more or less serious disadvantages. It is generally desirable for opening arrangements that they should be openable without the help of tools, that after the opening they should present a pouring opening with a smooth and well-defined edge, that the pouring opening should allow pouring out of the liquid contents in a uniform and collected jet, and that the pouring opening should be reclosable. Since the packing laminate is flexible and relatively tough, it is difficult to provide an opening arrangement which in a satisfactory manner meets all the abovementioned requirements. It has been found to be particularly difficult, for example, to provide an opening arrangement applied to the outside of the packing container which makes it possible, without major expenditure of force, to breach the packing laminate so that a pouring opening is generated, since the laminate is flexible and tough and the tearing of holes in it is difficult. It is possible, of course, to provide already during the manufacture of the packing laminate a pouring opening, which subsequently is covered with an appropriately designed external opening device, but such an arrangement is unsuitable on aseptic types of packing containers, since owing to the inclusion of a hole in the packing laminate continuous sterility cannot be guaranteed.